Hi. Just read this thread on 08/03/2019
I have one key for my is200 (3 button master)
I called lexus and a replacement is £90.40 plus vat. There's an additional labour cost for programming which I'm advised is about 15mins at £25
The key comes precut if you provide your reg
It's probably not relevant but it was with lexus Stockport. Gino was very helpful in servicing